The present invention relates generally to a survey instrument and methods for surveying. More particularly, the invention relates to a survey instrument for measuring elevational variations in local terrain, and two methods of conducting small scale engineering surveys.
Engineering surveys provide information for use in preparing topographical maps utilized in planning construction projects and other engineering related activities. In large scale surveys, aerial photography is commonly used, especially for mapping broad contour lines and similar details. For smaller scale surveys, various field instruments have been utilized with the selection of instrument depending usually upon the type of terrain involved and upon the quantity and quality of survey measurements needed.
In field surveys requiring accuracy of measurement a conventional instrument such as a transit is often used, frequently with an attached compass. The instrument with its tripod base is generally placed on the terrain over a known point by means of a plum bob or an optical plummet, and its telescope is aimed at a distant conventional range pole placed vertically on a second point of terrain. Range poles may include means such as disclosed in the Hein U.S. Pat. No. 723,526 dated Mar. 24, 1903, for facilitating vertical positioning of the rod or means such as disclosed in the Haun U.S. Pat. No. 3,685,162 dated Aug. 22, 1972, for positioning the rod vertically for an extended period on an uneven terrain surface.
Measurements generated by using a transit and range pole normally include (1) a vertical or elevational angle between the horizontal and a line from the transit to a known point on the range pole, (2) a horizontal angle or azimuth of the plane of the vertical angle relative to a selected compass heading, and (3) the approximate distance between the known point and the range pole, which is often determined by a steel tape of known length when accuracy is required.
Survey measurements thus generated may thereafter be analyzed to prepare a topographical map approximating features covered by the survey. The approximation may be presented, if desired, as a visual or coordinate display for purposes such as determining cuts and fills of land to be graded in which case a computing device, such as disclosed in the Hallisey U.S. Pat. No. 2,928,176 dated Mar. 15, 1960, may be utilized.
Although the transit and range pole are well known, they have various disadvantages when used in small scale engineering surveys. The survey information, although of high quality in terms of accuracy of vertical and horizontal angles, is time consuming and expensive to conduct, and normally requires at least two people and, preferably, a third person for recording information, especially if measurements are needed in large quantity with close spacing between measuring points. Also, the selection of measuring points may be limited by trees, rough terrain, structures, and other obstacles obscuring line of sight between the instrument and the range pole. And finally, in many small scale engineering surveys such as those involving landscape and landfill work or water flow analysis, high accuracy of angle measurements is not needed. Of more usefulness are measurements which may be obtained with relatively minimal time and expense, with close spacing between measuring points, and with little regard to obstacles present in the area to be surveyed.
Other known field survey instruments include the surveyor's compass and spirit level. However, because each of these instruments has a tripod base, the above described disadvantages in using a transit are not avoided and neither instrument has the measurement capability of a transit, i.e., a surveyor's compass measures only azimuthal angles and then not with the precision possible when using a transit, and a spirit level only measures vertical angles which limits its usefulness principally to measuring direct elevational differences between selected points of known spacing.
Still other known instruments include elevation meters such as those disclosed in the Eisler U.S. Pat. No. 2,613,449, dated Oct. 14, 1952, and grade measuring devices such as those disclosed in the the Bachfield U.S. Pat. No. 1,256,097 dated Feb. 12, 1918, the Werner U.S. Pat. No. 1,320,352, dated Oct. 28, 1919, the Noble U.S. Pat. No. 2,879,598 dated Mar. 31, 1959, and the Matsui U.S. Pat. No. 3,562,917 dated June 5, 1968. However, none of these instruments has the measuring capability of a transit.
It is accordingly an object of the present invention to obviate the above described deficiencies and provide a novel field survey instrument and methods of conducting a small scale engineering survey.
It is another object of the present invention to provide a field survey instrument and method for measuring both vertical and horizontal angles in relation to desired measuring points without the aid of additional instruments or a surveyor's assistant.
It is still another object of the present invention to provide a novel means and method for conducting a small scale engineering survey yielding reasonably accurate measurements of elevational variations in terrain in large quantity with reduced expense.
It is still a further object of the present invention to provide a rapid means and method for surveying local terrain with close spacing between survey measurments to provide a useful approximation of topographical features thereof.
It is still another object of the present invention to provide a simple means and method for surveying local terrain having obstacles to line of sight vision and unexpected variations in terrain elevation.
It is yet another object of the present invention to provide a means and method for measuring elevational variations in local terrain and rapidly recording and processing the measurements to provide a visual and coordinate display of topographical features for desired engineering purposes.
These and many other objects and advantages will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims and the following detailed description of the preferred embodiments when read in conjunction with the appended drawings.